In the pneumatic or hydraulic fields, functional equipment is fed with control or power fluid that is delivered thereto via a tube that needs to be connected in leaktight manner to an internal channel of the equipment. To do this, the body of the equipment is provided with a bore or well that opens out into one of its outside surfaces, and that has the fluid-feed channel terminating in its bottom. The connection means of the tube are for placing in the bore in leaktight manner. The connection means may be embodied in numerous ways on the tube end. On the equipment, there is either a tapped well for making a screw connection with a sleeve that carries the connection members of the tube, or else there is a well in which a sleeve becomes anchored. Anchoring is provided by teeth that are machined on the outside surface of the sleeve and that co-operate with the well after the sleeve has been engaged under force in the well. This engagement requires special tooling for it to be performed, and it gives rise in the engaged parts to permanent stresses and tensions that harm their lifetimes and that can give rise to microcracks leading to a coupling that leaks or indeed to the coupling spontaneously disconnecting.
Attempts have therefore been made to eliminate stresses from this type of connection and to reduce assembly forces. The known solution makes use of an intermediate structure (washer) between the sleeve and the well, which intermediate structure is elastically retractable on being engaged and, under a pull-out force, grips either to the sleeve or to the well by biting into the corresponding surface or by placing the sleeve or the well behind a shoulder that was passed during engagement. That type of connection presents the drawbacks of possessing a radial size that is not negligible, thereby penalizing either the working section for passing fluid through the connection, or else increasing the overall size of the coupling that is to be inserted in the well, which requires wells to be made of greater diameter and thus impeding the provision of a set of couplings arranged side by side on a baseplate of the equipment that is to be fed with fluid.
The beginning of a solution to this problem can be found in document FR 2 102 518. That document discloses an intermediate structure that is not in the form of a toothed washer, but rather in the form of a toothed cylindrical ring, the ring being received in an outer groove of the sleeve that is inserted in the well and biting into the inside surface of the well. The flexibility of the teeth is small and their fastening power is relatively weak.
In addition, that connection cannot be disassembled without destroying at least the toothed ring. In order to enable a gripped-together connection to be disassembled by applying rotation, it is known that the active portions of the teeth need to be given a slope such that the bite mark made by each tooth in the surface that it grips is tangential to a helix lying in the surface, as contrasted to being tangential to a circle lying therein. The major drawback of such gripping and unscrewable connections lies in the fact that they can become unscrewed spontaneously under the effect of axial forces between the two connected-together elements.
The invention provides a solution to each of these presently poorly-solved problems.